Relationship Between Dynamic Strength And Static Strength Of Concrete

In civil engineering, concrete structures often suffer dynamic loadings. Earthquake is very important for dynamic analysis of concrete structures especially for high arch dams. Thus, it is very important to analyze the dynamic properties of concrete and present reasonable and practical model which is the base of dynamic analysis of concrete structures. Regulations generally prescribe that, for anti-seismic strength calculating of hydraulic concrete structures except which have steel bars in them, dynamic strength and dynamic elastic modulus would increase about 30%. These regulations are obviously wrong. Because of different rate effect, concrete strength which has close correlations with some other concrete characteristics can't be of the opinion that it has the single increased result.The paper analyses the mechanics properties of concrete under dynamic load on the basis of dynamic equation. It uses the single axis experiment to find the distinction between"actual dynamic strength"and"theory dynamic strength". Considering the influence of water viscosity and dynamic inertia, it finds the equilibrium among the entire influence elements with the help of program simulating and statistics calculating and addresses the conclusion that increasing parts are viscosity force and inertia force. Then it work out actual dynamic strength value and send out the challenge for the former regulations. At last, considering the theories of"strength is the inherent property of materials"and"microcosmic description of concrete", it takes the judgement that the dynamic strength of concrete is equal to the static strength.Then the paper analyses the problem of how to ascertain the damping coefficient in dynamic experiment. To summarize relationship between different damping coefficient values and different loading speed rates, it establishes different damping coefficient values and different project situations and proves that it is wrong to unify the damping coefficient (5%common) in different dynamic designs. At last, it gives specific damping coefficient values for project situations with different load speed rates.Then the paper uses some practical experiments to prove the correctness of the simulation. These experiments show the changes of loads and strains. We could also find that it is wrong to consider dynamic strength increased during the dynamic loading situations. Only the program simulation is not enough, so the paper gives the example of Koyna Dam finally.Combining the theory and example, the final viewpoint appears more authentic and logical.